Keyboard lock



June 23, 1970 R. A. SHURTLIFF 3,516,529

KEYBOARD LOCK Filed Jan, 26, 1968 INVENTOR.

Rg ssm A Suumurr ATTORNEY United States Patent 3,516,529 KEYBOARD LOCK Russell A. Shurtlitf, San Leandro, Califi, assignor to The Singer Company, a corporation of New Jersey Filed Jan. 26, 1968, Ser. No. 700,833 Int. Cl. B41j 5/22 US. Cl. 19 7107 4 Claims ABSTRACT OF THE DISCLOSURE In a keyboard, a normally slack tape extends under the key bars, and is pulled taut by an electric magnet to block the key action. 7

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to mechanical locks for the keys of a keyboard.

SUMMARY OF THE INVENTION The invention provides a machine operable lock for preventing manual operation of a keyboard. It is advantageous for telegraphic transmission computer input and the like for locking the keyboard when the equipment cannot receive the data.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT A photoelectric keyboard includes a light source 12, a curved mirror 14, coded light shutters or blade portions 16 and 18, a mask 20 and photoelectric cells 22. The mirror 14 directs light through the parallel light channels defined by the aligned openings in the shutters 16, 18 and the mask 20. Each shutter 16, 18 is connected to a keytop 24 and a resilient boot 26 which holds it in normally raised position. Each shutter 16, 18, when depressed, alters the pattern of the light falling on the photoelectric cells 22 for coding the output of the cells 22.

A rack 30 and a strand, or tape, 32 are provided below the array of shutters 16, 18 and mounted on base portion 33. The rack 30 has webs or teeth 34 with channels or slots 36 between them, into which the shutters 16, 18 move when depressed. As a shutter 16, 18 moves down into a channel 36, its lower, advancing, edge 19 pulls a loop in the tape 32 as shown at shutter 18 in FIG. 1. The depression of such a shutter 16, 18 takes up a certain amount of slack in the tape 32. The slack may be suflicient to permit the depression of only one shutter 16, 18, or, alternatively, suflicient slack may be provided to permit the depression of two or more shutters 16, 18 simultaneously, as may be desired, as described in the copending application of Fred M. Sanchez, Ser. No. 685,033, filed Nov. 22, 1967.

The upper surface 35 of each of the webs 34 constitutes an abutment edge over which the tape 32 may be drawn when the bottom, or advanceable, edge 19 of a shutter 16, 18 moves down, or advances, into the channel 36, that is, into overlapping relation with the abutment edges 35 of the flanking webs 34.

The tape 32 also extends between two opposed serrated,

or toothed, members 38 and 40 having toothed portions 39 and 41, respectively. The upper of these is carried by the armature 42 of an electromagnet 44 which is pivotally mounted at 45 to a stationary member 47 carried by base portion 33. When electromagnet 44 is energized armature 42 is attracted thereto, pivoting about points 45, and teeth 41 of the upper block 40 are moved into the serrations of the lower block 38 for taking up slack in the tape 32. When the electromagnet 44 is deactuated, bias spring 49 attached to post 51 and armature 42 as shown urges upper block 40 away from lower block 38.

One end of the tape 32 is held by a clamp 46, FIG. 1, and the other is held by a take-up device 48. When the apparatus has been assembled, one or more shutters 16, 18, according to the number of shutters 16, 18 required to be depressed simultaneously, are depressed and the take-up device 48 is adjusted by rotating screw 50 to take the slack out of the tape 32 and leave it taut. The toothed members 38 and 40 are provided with sufficient teeth that the operation of magnet 42 will take up all of this slack, and prevent the operation of any of the keyoperated shutters 16, 18.

Conveniently, the shutters 16, etc., the rack 30, and the members 38 and 40 are made of a synthetic plastic material such as glass-filled nylon. It is desirable that the surfaces 35 that are engaged by the tape 32 be smooth so that the tape 32 moves over them easily. The tape 32 should be made of a strong, flexible, smooth and stable material. I have found that a suitable material for the tape 32 is the synthetic plastic material known as Mylar (said to be a trademark), which material is thought to be a polyester consisting of a polymerized terephthalate of one or more glycols, principally ethylene glycol. Mylar is strong and highly flexible, is not hygroscopic, and has a smooth, low friction surface. Although Mylar tape will stretch somewhat if abused, as when too many keys 24 are depressed at the same time with forces considerably greater than required for normal key operation, it will recover its original dimensions when left slack, as when the keyboard is left idle. Preferably, the tape 32 consists of four layers of Mylar, each .0005 inch thick and onequarter inch wide.

What is claimed is:

1. A keyboard comprising:

a base portion;

a plurality of keys each having a blade portion, said blade portions extending spaced from and substantially parallel to each other and being reciprocable between an actuated and a nonactuated position;

an elongated rack extending transversely of said blade portions and having a plurality of upstanding teeth forming a plurality of slots substantially parallel to said blade portions and aligned therewith;

each said blade portion having an advanceable edge arranged to lie in the slot aligned therewith when in said actuated position;

a flexible, substantially inextensible member loosely disposed transversely of said blade portions along the top of said teeth with a predetermined amount of slack therein and adapted to be drawn into said aligned slots in response to the actuation of said keys;

said blade portions being arranged on the opposite side of said member from said rack and in noncontactual relation with said member when in said nonactuated position;

anchor means coupled to the ends of said member for holding said ends in fixed position relative to said base portion and for providing said predetermined amount of slack;

and keyboard lock-up means for rendering said keys 4 inoperative, said keyboard lock-up means comprising 3. The combination of claim 1 wherein the surface a first member coupled to said base portion and havdistance along said toothed portion in a direction parallel ing an upper serrated portion, a second member reto said rack is substantially equal to said amount of preciprocably mounted in relation to said first member determined slack. and having a toothed portion aligned with said ser- 5 4. The combination of claim 1 wherein said anchor rated portion, said flexible member being interposed means includes take-up 'means coupled to one end of said between said serrated portion and said toothed porflexible member for varying said predetermined amount tion, and actuating means coupled to said second of slack. member for moving said toothed portion into mating References Cited relation with said serrated portion in response to a 10 UNITED STATES PATENTS predetermined signal to draw into the mating region between said toothed portion and said serrated por- 232,692 9/1880 Costa 197-107 tion an amount of said flexible member sufficient to 2'060431 11/1936 Splcer 197107 X prevent the operation of said keys, said actuating 3'032'168 5/1962 Reynard means comprising an electromagnet mounted on said 15 9 10/1963 Debus 1971'07 base portion, an armature pivotally mounted at one 3366216 1/1968 schonield et a1 197 107 end to said base portion, said second member being 2/1968 Augennos et 197107X mounted to the other end of said armature, and bias FOREIGN PATENTS means coupled to said armature for urging said sec- 15 468 1914 Great Britain. 0nd member away from sald first member. 20 1052696 12/1966 Great Britain.

2. The combination of claim 1 wherein said first and said second members are disposed along said flexible ERNEST WRIGHT JR Primary Examiner member between said rack and said anchor means. i i 

